1. Field of the Invention
The present invention relates to a digital broadcasting system, and more particularly to a method and an apparatus for transmitting/receiving mobility information to support the handover and roaming in a CBMS (Convergence of Broadcasting and Mobile Services) system.
2. Description of the Related Art
As generally known in the art, mobile broadcasts are recently provided by broadcasting systems or mobile communication systems in line with the development of communication and broadcasting technology. There are also discussions about mobile broadcasts that can transmit packet data through broadcasting channels, besides conventional broadcasting services that are limited to sounds and images. Mobile broadcasts are provided through a sequence of operations including the discovery of a service by a mobile terminal (e.g. mobile telephone, laptop computer, PDA) capable of receiving mobile broadcasts, subscription to the service by the mobile terminal, provision of various types of control information necessary to receive the service, transmission of the service, and reception of the service by the mobile terminal.
The OMA (Open Mobile Alliance) is one of the groups that are studying standards for the interworking between separate mobility solutions, and is mainly in charge of establishing various application standards regarding mobile games, Internet services, etc. One of the working groups of the OMA, particularly a sub-working group of the OMA BAC (Browse and Content) BCAST (Mobile Broadcast) is studying technology for the convergence of broadcasting and mobile services (CBMS) using mobile terminals capable of communicating with interactive networks. In addition, the DVB-CBMS (Digital Video Broadcasting-Convergence of Broadcasting and Mobile Services), one of the organizations for standards regarding mobile broadcasts based on mobile terminals, is defining the system structure, interface, etc., which are necessary for the CBMS.
In general, terminals adapted to receive broadcasting services in a mobile broadcasting system receive an ESG (Electronic Service Guide), which includes information regarding the service itself, billing, and method for receiving the service, and then receive a desired service by using the ESG.
When a terminal in a mobile broadcasting system moves from a home network (i.e. network of the home service provider to which the terminal user has subscribed) to a visited network (i.e. network of a foreign service provider), the user wants to receive broadcasting services from the home network or services from the foreign service provider, which has a roaming agreement with the home service provider, by using the terminal carried with him/her. This procedure is called roaming. When the terminal moves from the home network to the visited network while receiving a broadcasting service, the user wants to receive the broadcasting service seamlessly through the terminal. This procedure is called a handover.
However, conventional CBMS systems do not provide a definite procedure for the roaming and handover of broadcasting services. Therefore, technology for efficiently providing the roaming and handover of broadcasting services in a mobile broadcasting system is necessary.